This invention relates generally to a bearing cage for retaining balls of a ball bearing assembly in correct tangential position and, more particularly, to a two-piece bearing cage that may be molded of plastic or other material.
The use of bearing cages to maintain balls in their correct relative positions in a bearing assembly is well known. Typically, these bearing cages are injection molded of polyamide or filled polyamide resins. These cages are generally both functional and cost effective. However, a major problem associated with these cages is that their use in high temperature applications is restricted by upper temperature operating limits of 250 to 300 degrees Fahrenheit.
Bearing cages used in higher temperature applications are generally made of metal. These cages, which may be one or two-piece designs, are made of stamped or machined steel or the like. In the case of two-piece designs, the parts may be joined by welding, riveting or mechanical interlock. Some disadvantages of metal cages are that they are expensive, difficult to assemble and to visually inspect, and noisy in operation. Other problems include poor lubrication and inadequate heat dissipation.
High temperature polymers, such as polyetherketone (PEK) or polyetheretherketone (PEEK), capable of operating at temperatures up to 600 degrees Fahrenheit, are available. However, these high temperature polymers are brittle, having a much higher modulus of elasticity than more traditional types of plastic resin. In current designs, cages are molded with fingers or tabs projecting from them to hold bearing balls in position. When cages are made of high temperature polymers, such fingers or tabs fracture under the deflection required to remove the cages from their molds or to assemble the ball bearing assemblies.
The foregoing illustrates limitations known to exist in present bearing cages. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.